1. Technical Field
The present disclosure relates to an LED lighting apparatus, and more particularly, to a control circuit of an LED lighting apparatus, which has a voltage buffer function.
2. Related Art
According to the recent trend of lighting technology, an LED has been employed as a light source, in order to reduce energy.
A high-brightness LED is differentiated from other light sources in terms of various aspects such as energy consumption, lifetime, and light quality.
However, a lighting apparatus using the LED as a light source requires a large number of additional circuits for current driving, because the LED is driven by a constant current.
In order to solve the above-described problem, an AC direct-type lighting apparatus has been developed.
In general, the AC direct-type LED lighting apparatus is designed to drive an LED using a rectified voltage obtained by rectifying commercial power.
Since the AC direct-type LED lighting apparatus directly uses the rectified voltage as an input voltage without using an inductor and capacitor, the AC direct-type LED lighting apparatus has a satisfactory power factor.
Each of the LEDs included in the LED lighting apparatus may be designed to operate at 2.8V or 3.8V, for example. Depending on cases, the LED lighting apparatus may be designed in such a manner that a large number of LEDs connected in series emit light using a rectified voltage.
The LED lighting apparatus may be configured in such a manner that the LEDs of each group are sequentially turned on/off according to the rise/fall of the rectified voltage.
The LED lighting apparatus may be driven in various environments. In particular, the LED lighting apparatus may be driven by a voltage higher than a design value due to the power system environment or unstable power characteristic of the region in which the LED lighting apparatus is used.
That is, the LED lighting apparatus may be driven in a state where an over voltage equal to or more than a voltage required for operating LEDs is applied. In this case, an over current may be generated by the over voltage.
The above-described over current may have an influence on a current control circuit of the LED lighting apparatus. In a severe case, internal parts may be damaged by a malfunction or thermal stress caused by heat generation. In particular, an integrated circuit chip including the current control circuit may be damaged.
Recently, the demand for an LED lighting apparatus with a large capacity has been gradually increasing. In the case of the large-capacity LED lighting apparatus, the influence of the over voltage may be intensified. Then, the lifetime of the LED lighting apparatus may be reduced or the reliability of the LED lighting apparatus may be degraded due to a malfunction and part damage.